Chest compression apparatus for cardiac arrest

ABSTRACT

The invention is an apparatus for increasing intrathoracic pressure for resuscitating cardiac arrest patients. The apparatus comprises a flexible, substantially inelastic belt wrapped around the patient&#39;s chest and attached to a force converter. The force converter converts a downwardly directed force into a chestward resultant, which depresses the sternum, and two belt tightening resultants. The force converter comprises a pair of arm assemblies, each having a pair of spaced arms, which are pivotably mounted to a base. The base is positioned near the patient&#39;s sternum and the ends of the belt attach to one end of each arm assembly. The opposite, handle ends of the arm assemblies are depressed toward the chest causing tightening of the belt and compression of the chest cavity.

TECHNICAL FIELD

[0001] This invention relates broadly to the field of medical devicesand more specifically to an apparatus for increasing the blood flow bycompressing the chest cavity of a person suffering from cardiac arrest.

BACKGROUND ART

[0002] During cardiac arrest, it is desirable to generate blood flow byexternal means in order to maintain brain and heart viability.Traditionally, the external means of generating blood flow has beenmanual cardiopulmonary resuscitation (CPR). Using CPR, the rescuer tiltsthe patient's head back, lifts the chin to clear and straighten theairway, and depresses the sternum 1 ½ to 2 inches 15 times (at a rate of80 to 100 depressions per minute), after which the rescuer gives thepatient 2 full breaths. This 15 depressions and 2 breaths is repeatedcyclically.

[0003] Currently, the CPR research community believes that blood flowproduced by external means can be explained by one, or a combination oftwo, theoretical mechanisms: the “cardiac pump” mechanism and the“thoracic pump” mechanism.

[0004] According to the cardiac pump mechanism, blood flow caused byexternal means is due to direct mechanical compression of the heart.During compression, blood is squeezed out of the heart chambers, andduring release of the compression (relaxation) blood flows into theheart chambers. Backflow of the blood is prevented by the valving of theheart and vessels.

[0005] According to the thoracic pump mechanism, blood is pumped byexternal means as a result of the cyclical increase and decrease ofintrathoracic pressure. During compression, the intrathoracic pressurerises, which causes blood to be forced out of the blood vessels andorgans located in the thorax, and the blood flows into the peripheraltissues. During release, blood flows back into the thorax via the normalvenous return. In this method, backflow is prevented by the valving ofthe veins.

[0006] Most researchers believe that both mechanisms are active to somedegree. However, the methods presently in use, and the devices currentlyin use, for promoting blood flow by the application of an external forceare directed toward only one of the two mechanisms. In order to maximizeblood flow, a device which takes advantage of both mechanisms is needed.

[0007] A variety of devices have been developed to increase blood and/orair flow in the chest cavity of a cardiac arrest patient.

[0008] U.S. Pat. No. 2,071,215 to Petersen shows a piston and cylinderarrangement attached to two ends of a girdle which encircles a patient'schest. The expansion or compression of a fluid in the piston andcylinder combination tightens and loosens the girdle to ventilate thelungs. This device is large and heavy, and is dependent upon acompressed fluid for driving power.

[0009] U.S. Pat. No. 3,425,409 to Isaacson et al. discloses an apparatusfor compressing the sternum by a downward force generated by a piston. Abelt is placed around the chest in order to minimize bodily damage, andair is applied to the air passages of the patient.

[0010] U.S. Pat. No. 5,287,846 to Capjon et al. shows an upper framethat rests on a patient, whose back rests on a lower frame. Retractablestraps extend from the upper frame and attach to the lower frame. Ahydraulic cylinder in the upper frame presses downwardly on the chest.

[0011] Barkalow, in U.S. Pat. No. 3,461,860, discloses a device using apneumatic plunger to mechanically compress the sternum a predetermineddistance. A mechanical ventilator was added to this device in U.S. Pat.No. 4,326,507 to insure proper ventilation and increase the volume ofthe chest. This device was limited in its success due to complexitywhich requires trained personnel to use it.

[0012] A similar device was disclosed in U.S. Pat. No. 4,060,079 toReinhold. This device is merely a similar portable unit.

[0013] Bloom, in U.S. Pat. No. 4,338,924, shows a sternum compressiondevice using an air cylinder to depress the chest of the cardiac arrestpatient. This device, like many others using a chest compression design,is large and is heavy.

[0014] Newman et al., in U.S. Pat. No. 4,424,806, show a pneumatic vestfor generating a rise in thoracic pressure. This vest uses the “thoracicpump” concept of exerting greater force over a larger area under theassumption that if more major organs could be compressed and released,greater blood flow would occur. By releasing the compression force, thechest would return to its normal size and draw blood back into the majororgans. Positive blood flow would occur due to the one-way valves in thevascular network. The Newman device is not readily portable, in additionto having substantial complexity. In U.S. Pat. No. 4,928,674, Halperinet al. disclose a similar vest which is similarly not portable.

[0015] Lach et al., in U.S. Pat. No. 4,770,164, disclose acircumferential band and take-up reel used to generate a rise inthoracic pressure. Although either manually or mechanically driven, thisapparatus requires the use of a backboard for guiding the band aroundthe chest.

[0016] The use of bands or belts to generate a rise in intrathoraciccompression for the purpose of assisting respiratory ailments isdisclosed in U.S. Pat. No. 651,962 to Boghean. This device is forperiodic loosening and tightening of the band around a patient's chestfor treating respiratory disease by regulating periods of breathing aswell as the size or depth of breath.

[0017] In U.S. Pat. No. 3,777,744, Fryfogle et al. disclose a breathingaid consisting of a belt and a handle which tightens the belt forexpelling excessive residual air in the lungs.

[0018] Other devices known to the Applicants using circumferential bandsfor generating a compression force on the abdomen and lower chest toassist in compression of lungs for respiratory purposes include U.S.Pat. No. 2,899,955 to Huxley, U.S. Pat. No. 3,368,581 to Glascock andU.S. Pat. No. 2,754,817 to Nemeth. Furthermore, the use of inflatablebladders positioned around either the chest or the abdomen have beendisclosed in U.S. Pat. No. 3,481,327 to Drennen, U.S. Pat. No. 3,120,228to Huxley, U.S. Pat. No. 3,042,024 to Mendelson, U.S. Pat. No. 2,853,998to Emerson, U.S. Pat. No. 2,780,222 to Polzin, U.S. Pat. No. 2,071,215to Petersen, U.S. Pat. No. 4,424,806 to Newman and U.S. Pat. No.4,928,674 to Halperin.

[0019] U.S. Pat. No. 2,699,163 to Engstrom, shows a respirator devicefor ventilating a patient's lungs.

[0020] U.S. Pat. No. 5,295,481 to Geeham shows a chest compressiondevice comprising a T-shaped mechanical chest compression apparatus witha suction cup. The central shaft attached to the cup may be compressedbeyond the lips of the cup and bruise or otherwise injure the patientdue to the concentration of force on the patient by the shaft tip.

[0021] U.S. Pat. Nos. 4,397,306 to Weisfeldt et al. and 1,399,034 toTaplin show large mechanical devices for compressing the chest of acardiac arrest patient.

[0022] Szpur, in U.S. Pat. No. 5,407,418, discloses a power-driven,pulsating compressor apparatus for stimulating blood flow within vesselsof a person's foot or hand. The device periodically applies aconcentrated force against a localized region of the foot or hand.

[0023] In spite of the prior art, the need still exists for a devicewhich effectively increases the flow of blood in the organs of a cardiacarrest patient. This device should be truly portable and useable by aperson of average strength and skill.

BRIEF DISCLOSURE OF INVENTION

[0024] The invention is an apparatus for increasing the flow of blood ina patient, for example a person suffering cardiac arrest. The apparatuscomprises a base contoured to seat near a central region of thepatient's chest. Also included are a manual actuator and a substantiallyinelastic belt which is for wrapping around the patient's chest. Theinvention further comprises a force converter mounted to the base. Theforce converter is connected to the actuator and has belt connectors forconnecting to opposite extremities of the belt. The force converter isfor converting a force manually applied to the actuator and directedtoward the chest into a chest compressing resultant. The chestcompressing resultant is directed through the base toward the chest. Theforce manually applied to the actuator is converted, in addition to thechest compressing resultant, into belt tightening resultants applied tothe belt connectors, and directed tangentially to the chest.

[0025] The invention contemplates the converter comprising first andsecond assemblies. The first assembly has a pair of spaced, parallelarms rigidly connected at handle ends by a first hand-grippable handle.The arms of the first assembly are further rigidly connected atopposite, belt ends by a first strut. The first assembly arms arepivotally mounted to the base at a first assembly fulcrum intermediatethe handle and belt ends. The second assembly is substantially similarto the first assembly and both assemblies are pivotally mounted to thebase, forming a scissors arrangement. A force applied to the handle endspivots the scissoring assemblies, which form a pair of levers. The strutends of the assemblies are levered toward one another, tightening thebelt attached to the struts.

[0026] It is an objective of the present invention to provide anapparatus having a flexible belt which wraps around the chest of acardiac arrest patient. The apparatus tightens the belt while depressingthe chest, the combination of which raises the intrathoracic pressure,enhancing blood flow.

BRIEF DESCRIPTION OF DRAWINGS

[0027]FIG. 1 is a view in perspective illustrating an embodiment of thepresent invention in an operable position;

[0028]FIG. 2 is a side view in section illustrating the extremepositions of the arm assemblies of the embodiment of the presentinvention shown in FIG. 1;

[0029]FIG. 3 is a diagrammatic view illustrating a force diagram;

[0030]FIG. 4 is a diagrammatic view illustrating an alternative forceconverter;

[0031]FIG. 5 is a diagrammatic view illustrating an alternative forceconverter;

[0032]FIG. 6 is a diagrammatic view illustrating an alternative forceconverter;

[0033]FIG. 7 is a diagrammatic view illustrating an alternative forceconverter;

[0034]FIG. 8 is a diagrammatic view illustrating an alternative forceconverter;

[0035]FIG. 9 is a view in perspective illustrating an alternativeembodiment of the present invention;

[0036]FIG. 10 is an end view in section illustrating a prime moveractuator as part of the present invention;

[0037]FIG. 11 is a view in perspective illustrating an alternativeembodiment of the present invention;

[0038]FIG. 12 is a diagrammatic view illustrating an alternativeembodiment of the present invention;

[0039]FIG. 13 is a view in perspective illustrating an embodiment of thepresent invention;

[0040]FIG. 14 is an enlarged view in perspective of an embodiment of thepresent invention;

[0041]FIG. 15 is a side view in section illustrating the extremepositions of the arm assemblies of the embodiment of the presentinvention shown in FIG. 13;

[0042]FIG. 16 is a side view in section illustrating a sole of the base;and

[0043]FIG. 17 is a side view in section illustrating another sole of thebase.

[0044] In describing the preferred embodiment of the invention which isillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific terms so selected and it is to be understoodthat each specific term includes all technical equivalents which operatein a similar manner to accomplish a similar purpose.

DETAILED DESCRIPTION

[0045]FIG. 1 shows the apparatus 10, which is an embodiment of theinvention, in its operable position on and around a patient's chest 12.The base 14 is a semi-rigid (preferably plastic) plate or block,preferably having a cushioned outer surface contoured to seat againstthe central region of the patient's chest 12 near the sternum.

[0046] The sole 92 of the base 14 is seated against the upper surface ofthe chest 12 and may have an adhesive pad 500 (shown in FIG. 16) or asuction cup 502 (shown in FIG. 17) to adhere to the chest 12 so thatpulling on the base 14 will cause the chest 12 to be pulled fordecompression.

[0047] The base 14 contains a switch 70 and a pair of lights 72.Additionally, the base 14 contains a battery, a battery charge indicatorand a sound generator (not visible in FIG. 1) which sound generatoremits an audible, periodic signal. The visible and audible signalsindicate the frequency to a rescuer of a compressive force he or she isto apply to the apparatus 10. One or more of the audible or visiblesignals could also prompt the rescuer to apply ventilation. The base 14also contains a force sensor, such as a strain gauge, and an indicator74 which indicates the force exerted on the chest 12 to warn the rescuerof potential injury due to excessive force. A limiter could be added tolimit some of the force applied to the patient to a specified maximum.

[0048] The first arm assembly 16 is made up of a pair of spaced,parallel arms 22 and 24 which are made of high tensile strength,lightweight material such as plastic. The second arm assembly 18 hassubstantially similar spaced, parallel arms 26 and 28. A pair of rods 37and 38 rigidly fasten the spaced parallel arms of the assemblies 16 and18, respectively. A pair of manual actuators, which are preferably twocylindrical, hand-grippable handles 30 and 32, are rotatably mountedbetween the spaced, parallel arms of the first and second arm assemblies16 and 18, around the rods 37 and 38, respectively. A pair of rod-like,preferably metal struts 34 and 36 (strut 36 not visible in FIG. 1)rigidly mount to the ends-of the spaced arms, opposite the handles 30and 32.

[0049] The rigid arm assemblies 16 and 18 pivot relative to one anotherabout the pivot pin 20, which is preferably a stainless steel bolt. Thepin 20 extends longitudinally through the base 14 and extends out ofeach longitudinal end to pivotally attach to each arm 22, 24, 26 and 28.

[0050] The arm assemblies 16 and 18 are arranged in a scissor-likeconfiguration. This configuration is designed to convert a small forceinto a larger force. This is done by the scissor-like configurationhaving a pair of levers with a common fulcrum, where the fulcrum islocated a distance from the center of the levers. A large displacementof the handles 30 and 32 causes a relatively small displacement of thestruts 34 and 36. In elementary physics, it is understood that workequals force times distance and the force applied to cause adisplacement at one end of a lever should equal the product of force anddisplacement at the opposite end of the lever. Conservation of workgives

F_(s)D_(s)=F_(h)D_(h)  Equation 1

[0051] where the subscript s indicates the force or displacement at thestruts 34 and 36 and the subscript h indicates the force or displacementat the handles 30 and 32. Solving Equation 1 for the force at the struts34 and 36 obtains $\begin{matrix}{F_{s} = {\frac{F_{h}D_{h}}{D_{s}}.}} & {{Equation}\quad 2}\end{matrix}$

[0052] The displacement at the struts 34 and 36 (D_(s) in Equation 2)will always be smaller than the displacement at the handle (D_(h) inEquation 2). By separating the displacement part of Equation 2 inparenthesis, the following is obtained: $\begin{matrix}{F_{s} = {{F_{h}\left( \frac{D_{h}}{D_{s}} \right)}.}} & {{Equation}\quad 3}\end{matrix}$

[0053] Since the displacement at the struts is smaller than thedisplacement at the handles, the displacement portion of Equation 3 willbe a number greater than 1 which, when multiplied by the force at thehandles, will obtain a force at the struts which is greater than theforce at the handles. It is this greater force at the struts 34 and 36,effected by the force applied to the handles, which is used toartificially induce or enhance blood flow in a patient.

[0054] The pivoting motion of the arm assemblies 16 and 18 is a simpleand reliable action which virtually any person can effectuate. Doing sorequires a small force, and creates a larger force that is to be appliedto a patient's chest 12. The force at the struts 34 and 36 could not begenerated by an average person for the time period required to treat acardiac arrest patient, without the help of a mechanical device.

[0055] Two stainless steel stroke limiters 52 and 54 are pivotallymounted to the arms 22 and 24 and slidingly attach to the arms 26 and28. The limiters 52 and 54 serve the purpose of limiting the relativepivoting displacement of the assemblies 16 and 18 by mechanicallyrestricting their movement. Unlimited displacement between the twoassemblies 16 and 18 could result in an excessive compression force onthe chest 12 which could injure the patient.

[0056] An alternative to the arm assemblies 16 and 18 shown in FIG. 1 isthe arm assemblies 416 and 418 shown in FIG. 13. The arm assemblies 416and 418 are made up of the spaced, parallel arms 422, 424, 426 and 428,respectively. The curved shape of the arms 422-428 making up the armassemblies 416 and 418 has been found to be more advantageous than theangled shape of the arms making up the arm assemblies 16 and 18 shown inFIG. 1. The advantage is found primarily in the means for limiting therelative displacement of the arm assemblies 416 and 418. The preferredmeans for limiting the relative displacement is shown in greater detailin FIG. 14.

[0057] As the arms 422 and 426, shown in FIG. 14, pivot about the commonfulcrum located at the pivot pin 430, they pivot toward the stop pin432. The stop pin 432 extends through one of three holes formed in anupright 434 which extends rigidly from the base 414. The arm 422 hasthree shoulders 440, 442, and 444 which face the stop pin 432. The arm426 has three similar shoulders 446, 448 and 450. In their relaxedposition shown in FIG. 14, the arms 422 and 426 have gaps of apredetermined distance between corresponding shoulders. For example, thegap between shoulder 442 and shoulder 448 is a predetermined size whenthe arms 422 and 426 are in their relaxed position. As the arms 422 and426 are pivoted toward one another, the gaps between the shouldersdecrease in size. In order to insure that the gap between a particularpair of shoulders does not decrease below a specified minimum, the stoppin 432 is placed in one of the three holes 452, 454 or 456 formed inthe upright 434. Each hole has an axis which extends into a particulargap. Since the three gaps between the six shoulders 440-450 are ofdifferent length, the position of the stop pin 432 in the upright 434will affect the distance the arms 422 and 426 can travel until twoassociated shoulders seat against the stop pin 432, restricting furtherdisplacement.

[0058] For example, FIG. 15 shows the arm assemblies 416 and 418 intheir relaxed positions and in phantom in an extended position. In theextended position, when the stop pin 432 is positioned in the hole 456of the upright 434, the shoulders 440 and 446 seat against the stop pin432 to limit the extension of the arm assemblies 416 and 418.

[0059] The belt 40, which extends around the front, sides and back ofthe chest, is substantially inelastic and flexible. A plurality ofindicia 50 is imprinted on the exposed surface of the belt 50. The belt40 attaches to the strut 34 on one side of the chest 12, and extendsaround a major portion of the circumference of the chest 12 to attach tothe other strut 36. When the assemblies 16 and 18 pivot around the pivotpin 20, the belt 40 is tightened by the struts 34 and 36 to which thebelt 40 attaches.

[0060] Although the belt 40 is described as extending around the front,sides and back of the chest, the belt may be made up of two or morecomponent parts, such as a pair of belts. This pair of belts couldextend from attachment to the struts 34 and 36, extending downwardlypast the sides of the patient's chest to rigid attachment to a boardwhich spans the width of the back of the chest. Therefore, “a beltwrapped around the chest” can be made up of two or more belt componentswhich extend around portions of the chest circumference in combinationwith other rigid or flexible components.

[0061] The relaxed and mid-actuated positions of the arms of theapparatus 10 are shown in FIG. 2. The first and second assemblies 16 and18 are shown in their relaxed position and (in phantom) at the mid-pointof their actuated position. The assemblies 16 and 18 are biased into therelaxed position by a spring (not shown) which could be a torsion springextending around pin 20 and connecting to the assemblies 16 and 18. Thehandle ends 80 and 82 of the arms 22 and 26 pivot along an arcuate pathdownwardly and away from each other, and the belt ends 84 and 86 of thearms 22 and 26 pivot upwardly and toward one another in an arcuate pathsubtending the same angle as the handle ends 80 and 82. The beltextremities 88 and 90 (which are the looped ends of the belt 40 whichattach to the struts 34 and 36) follow the belt ends 84 and 86 of thearms to an upward and more proximally spaced position. Since the belt 40is substantially inelastic, its circumference will decrease under theforce applied to it by the struts 34 and 36, thereby tightening the belt40 around the chest 12.

[0062] The belt 40 extends through slots 44 formed in a backboard 42which, when in use, is positioned beneath the chest 12 of the patient.The belt 40 preferably seats against a sliding mechanism 43 whichpermits sliding of the belt 40 along the length of the chest 12 forpositioning of the belt 40 on the chest 12. The backboard 42 is made ofa strong, lightweight material such as plastic and is wide enough tospan the width of the chests of a large majority of the population. Thebackboard 42 has a padded, raised portion 46 which elevates thepatient's neck above his head for opening the breathing passages, andthe backboard 42 preferably has handles 250 and 252 (shown in FIG. 9)for carrying the backboard 42 with or without a patient lying on it. Thebackboard 42, the attached belt 40 and the assemblies 16 and 18, are allhung on a wall by extending hooks through the handles 250 and 252 or bysome other conventional hanging means, and may be hinged near the centerfor folding during storage.

[0063] An oxygen tank 100 and a mask 102 are shown in hidden lines inFIG. 2 as contained within a chamber 104 formed in the backboard 42. Agauge 103, indicating the amount of oxygen in the tank 100, is visiblethrough the port 101. The raised portion 46 of the backboard 42 issuited to the formation of a cylindrical chamber 104 in which the oxygentank 100 can be easily stored. If needed, the mask 102 can be withdrawnfrom the chamber 104 and placed over the patient's mouth for enhancedventilation of the patient's lungs.

[0064] The apparatus 10 is operated in the following manner, referringto FIGS. 1 and 2. The victim is placed onto the backboard 42 with his orher chest 12 in the position shown in FIG. 1. The back of the patient'schest 12 seats against the surface of the backboard 42 with thepatient's neck resting on the raised portion 46 and his head lying onthe horizontal surface on which the backboard 42 lies, such as a floor.The base 14 of the apparatus 10 is placed at approximately the center ofthe patient's chest 12 near the sternum. The belt 40 is then extendedupwardly from the backboard 42, between the arms and chest 12, andaround opposite sides of the chest 12 to match the relaxed contour ofthe chest 12. The belt 40 is positioned as high on the chest 12 and ashigh under the underarms as possible.

[0065] The belt 40 is next extended around the struts 34 and 36, passingfirst between each strut 34 and 36 and the base 14. The base 14 is moreexactly positioned near the center of the chest 12 by matching theindicia 50 on the belt 40 on opposite sides of the base 14. The indicia50 are alphanumeric characters spaced equally along the length of thebelt 40 in a preferably identical arrangement at both ends of the belt40. The indicia could, of course, be colored bands or other symbols.

[0066] Once the belt 40 extends around the struts 34 and 36, the ends ofthe belt 40 are folded back over onto the portion of the belt 40contacting the chest 12 and are attached thereto by fasteners. Beforefastening, though, the indicia 50 at both struts 34 and 36 must match.For example, the number “3” is shown as the highest number on the belt40 visible in FIG. 1. In this example, the same number (“3”) should bethe highest number visible at both struts 34 and 36, which indicatesthat an equal length of the belt 40 extends from the backboard 42 to thestrut 34 as to the strut 36, and therefore that the base 14 is centeredon the chest 12.

[0067] After fastening the belt 40 to the struts 34 and 36, the strokelimiter pins 60 and 62 extend into the holes 1 and 4 in the arms 26 and28. Since the number “3” is the highest visible number on the belt 40,the limiter pins 60 and 62 are placed in the distal of the six holes 1-6in arms 26 and 28. If the number “2” were the highest number visible onthe belt 40, the center holes 2 and 5 of the six holes 1-6 on the pivotarms 26 and 28 would be used, since the number “2” would indicate alarger chest circumference than when “3” is the highest visible number.The stroke when the number “2” is the highest visible number is greaterthan when “3” is the highest visible number. This means for a largerchest circumference, the apparatus would be permitted to cause greaterdisplacement of the chest 12.

[0068] If the arm assemblies 416 and 418 shown in FIG. 13 are usedrather than the arm assemblies 16 and 18 shown in FIG. 1, then thehighest number visible on the belt 40 would indicate the positioning ofthe stop pin 432 in the upright 434. For example, since the number 3 isthe highest number visible on the belt 40 in FIG. 1, the stop pin 432would be placed in the hole 456 which has the indicium “3” next to it.The indicium “3” is visible in FIG. 15, but only the indicia “1” and “2”can be seen in FIGS. 13 and 14.

[0069] Once the apparatus 10 is positioned with the belt 40 around thechest 12, the base 14 is centered and the limiters 52 and 54 are in thecorrect position for the visible indicia 50 on the belt 40, the rescuerdepresses the switch 70. This causes the lights 72 to begin emitting aperiodic, visible signal and the base 14 to emit a periodic, audiblesignal in synchronization with the lights 72. The rescuer then gripshandles 30 and 32 with his or her hands and, with a downwardly directedforce toward the chest 12, pushes the handles 30 and 32, pivoting themabout the pivot pin 20, thereby pivoting the arms 22, 24, 26 and 28through arcuate paths about the pin 20. This pivoting motion causes thestruts 34 and 36 at the opposite ends of the arms from the handles 30and 32 to pivot about the pivot pin 20 in a direction away from thechest 12, but with a smaller displacement than the handles 30 and 32.Pivoting of the struts 34 and 36 draws the ends of the belt 40 closertogether, thereby tightening the belt 40 around the chest 12. Since thebelt 40 is inelastic, tightening of the belt 40 compresses the chest 12.The arcuate motion of the handles 30 and 32 is limited to a maximumdisplacement by the stroke limiters 52 and 54, when the pins 60 and 62contact the ends of the slots 64 and 66. The force on the handles 30 and32 is released and then exerted again by the rescuer after the handles30 and 32 have returned to their original positions.

[0070] By cyclically depressing with a downwardly directed force, andreleasing the handles 30 and 32 (preferably in phase with the lights72), the rescuer cyclically tightens and loosens the belt 40 around thepatient's chest 12. The base 14 concentrates some of the tighteningforce of the belt in the chest 12 center and prevents pinching of thechest by the scissor-like assemblies 16 and 18. The belt 40 tighteningaround the chest 12 represents the “thoracic pump” method ofartificially inducing blood flow in a cardiac arrest patient by applyinga circumferential compressive force to a large area. The large force isfrom the leverage created by the scissor-like assemblies 16 and 18, andthe large area is the circumference of the chest 12.

[0071] As the first assembly 16 and the second assembly 18 are forceddownwardly toward the chest, the base sole 92 is forced downwardly alonga path directed into, and preferably perpendicular to, the chest surfaceby the downwardly directed force on the handles 30 and 32. Therefore,each depression of the first and second assemblies 16 and 18 results ina downward compression of the center of the chest by the base 14. Thisis the “cardiac pump” method of inducing blood flow by compressing theheart between the spine and the sternum.

[0072] Compressing the organs using the present invention takesadvantage of both the “thoracic pump” (belt tightening and loosening)and “cardiac pump” (chest depression by the base 14) methods to conveyblood through the blood vessels and, upon release, draw blood back intothe organs. Upon each increase in pressure, the blood is compressed outof the organs (and air out of the lungs) and along the vascular system.Upon release, other blood is pulled in. Since the veins have a series ofone-way valves, the periodic raising and lowering of thoracic pressurewith the present invention creates an artificial blood flow supplyingnecessary elements to the vital organs, such as the brain, whichincreases the patient's chances of survival.

[0073] The pivoting assemblies 16 and 18 comprise a force converterwhich converts the downwardly directed chest compressing force appliedto the handles 30 and 32 into multiple resultant forces. These resultantforces include a downwardly directed force applied from the base 14 intothe chest 12 and two equal tangential forces applied by the struts 34and 36 to the belt 40. The forces are applied tangentially to the chest12 since the belt 40 wrapped around the chest 12 and pulled taut must betangential to the chest 12 surface if it contacts the chest at the chestsides as shown in FIG. 1. The assemblies 16 and 18 comprise the forceconverter which is a device that converts the force manually applied tothe handles 30 and 32, and directed toward the chest 12, into theresultants described above (specifically, a chest compressing resultantand a pair of belt tightening resultants).

[0074] A converter for converting the above described applied force intothe resultants includes all equivalents to the preferred forceconverter. A converter need not merely redirect a specific force butcould amplify, reduce or signal a device to generate other forces, bythe application of a force.

[0075] The force necessary to generate sufficient pressure in the chestcavity to create blood flow can be generated by an average person if adevice utilizes an applied force correctly. In the position in which acardiac arrest patient is normally found, a rescuer cannot normally,without leverage, generate a downward force into the patient's chestsufficient to generate the necessary intrathoracic pressure without therisk of injury. The apparatus of the present invention uses the forcewhich an average person can apply and converts the applied force intoresultant forces in the directions needed while limiting the maximumdisplacement of the chest to prevent injury.

[0076] The force converter described above can be considered as a freebody shown in FIG. 3 having an applied force 112 directed downwardlyonto the converter 110. An opposite force 114 is applied by the chestagainst the converter 110 as a reaction to the opposite force 112. Thetangential forces 116 and 118 are the forces of the belt, extendingcircumferentially around the chest, pulling on the converter 110. Theconverter 110 converts the downwardly directed force 112 into resultantforces 120, 122, and 124. The resultant force 120 is directed into thechest along a direction similar to the applied force 112. The resultantforces 122 and 124 apply a tangential tension force to the belt which istangential to the patient's chest.

[0077] The preferred embodiment of the present invention is one devicethe Applicants have found advantageous for converting the downward force112 into the three resultant forces 120, 122 and 124. The Applicantsknow that many apparatuses are equivalent to, and could be substitutedfor, the preferred apparatus to provide the force conversion describedin association with FIG. 3. Although it is impossible to list everymechanical device which one skilled in the art will know can convert anapplied force into the desired resultant forces, some of the manyequivalents are described herein. However, this is not an exhaustivelist, and other equivalents exist as will become apparent to thoseskilled in the art.

[0078]FIG. 4 shows a diagrammatic illustration of a cam 140 and a pairof cam followers 142 and 144. Upon the application of a downward forceby the cam 140 onto a pair of inclined surfaces 143 and 145, thefollower 142 will slide rightwardly and the follower 144 will slideleftwardly, thereby exerting forces on the belt ends attached thereto,tightening the belt. The cam 140 will slide down the inclined surfacesof followers 142 and 144, and upon reaching the horizontal surfaces 146and 148, will stop abruptly—exerting a downward force onto the surfacebeneath the followers 142 and 144, which could be the base of thepresent invention. The apparatus of FIG. 4 is equivalent to thepreferred force converter apparatus.

[0079]FIG. 5 shows a diagrammatic illustration of a first eccentric 150and a second eccentric 152 pivotally mounted to a base 154. A manualactuator 156 attaches to a second pivot on each eccentric. A pair ofbelt ends 158 and 160 wrap around the eccentrics 150 and 152,respectively. Upon the application of a downwardly directed force on theactuator 156, the eccentrics 150 and 152 pivot about the pivot points,exerting a force on the belt ends 158 and 160 causing a tightening ofthe belt. The eccentrics 150 and 152 will, upon a sufficient downwardlydirected force on the actuator 156, impact upon the base 154, exerting adownwardly directed force on the base 154 as in the preferredembodiment. The apparatus of FIG. 5 is equivalent to the preferredembodiment.

[0080]FIG. 6 illustrates a diagrammatic illustration of anotherequivalent to the preferred embodiment including an actuator 170 towhich a downwardly directed force is applied. The actuator 170 has atwo-sided toothed surface 172 which inter-engages with a pair of gears174 and 176. Gears 174 and 176 are pivotally mounted to a base 178 and apair of belt ends 180 and 182 wrap around a pair of drums 184 and 186 ateach of the gears 174 and 176. The toothed surface 172, upon adownwardly applied force to the actuator 170, causes the inter-engaginggears 174 and 176 to rotate, thereby applying a force to the ends 180and 182 of the belt. The actuator 170 impacts the base 178 upon beingactuated to a certain extremity, thereby exerting a downwardly directedforce to the base 178 as in the preferred embodiment.

[0081] Another alternative, mechanical apparatus 260 which is equivalentto the preferred embodiment is shown in FIG. 11. The apparatus 260 has apair of pivoting arms 262 and 264 which pivot about a pivot axis 266 ona base 268. A belt 270 attaches at opposite longitudinal ends to thearms 262 and 264. The base 268 is positioned on a patient's chest 272,the belt 270 is extended circumferentially around the chest 272 andattached to the handles 262 and 264. A downwardly directed force isapplied to the handles 262 and 264, tightening the belt 270 as the arms262 and 264 pivot about the pivot pin 266. In addition to the tighteningof the belt 270, the base 268 is forced downwardly into the chest 272.

[0082]FIG. 12 shows a two-chamber device having a base 300 and twopivoting arms 302 and 304. Two springs 306 and 308 keep two arms 302 and304 biased upwardly within the chamber 310. A plunger 312 is biased awayfrom the chamber 310 by a spring 314. The belt 316 is attached to thearms 302 and 304. Upon downward compression of the plunger 312, the arms302 and 304 are rotated counterclockwise and clockwise, respectively.This rotation tightens the belt 316 and a patient's chest is compressedwith the tightened belt 316 and with the base 300, especially when theplunger 312 reaches the lower limit of the chamber 310.

[0083] Many illustrations show equivalent substitute devices forconverting an applied force into the desired resultant forces. Most ofthose described above show purely mechanical equivalents to thepreferred embodiment. As a person skilled in the mechanical arts willquickly find, there are many other different substitutes for thepreferred embodiment. These devices are equivalent to the preferredembodiment or one of the alternatives described above and shown in thedrawings. In addition to purely mechanical alternatives to the preferredembodiment, it is of course possible to combine mechanical, electrical,hydraulic and many other elements to arrive at an equivalent substitutefor the preferred embodiment. These combination equivalents arediscussed below.

[0084] In FIG. 7 a mechanical and electrical combination equivalent isshown diagrammatically including an actuator 200 and an electric motor202 attached to a base 204. The motor 202 has a pair of belt ends 206and 208 attached to a driveshaft 210. Upon depression of the actuator200, a pressure-sensitive switch 212 actuates the motor 202, rotatingthe driveshaft 210 and exerting a linear force on the belt ends 206 and208. As the force is applied to the actuator 200, this downwardlydirected force is transmitted through the base 204 to the patient'schest which lies directly beneath the base 204. The embodiment of FIG. 7is equivalent to the preferred embodiment.

[0085]FIG. 8 shows still another equivalent to the present invention ina diagrammatic illustration including a hydraulic cylinder 220, fluidlines 222 and 224, and pistons 226 and 228 slidingly mounted within thecylinder 220. The belt ends 230 and 232 are mounted to the pistons 226and 228. Upon actuation of an actuator 234, hydraulic fluid is forcedinto the hydraulic cylinder 220 forcing the pistons 226 and 228 towardone another longitudinally, thereby exerting a force on the belt ends230 and 232. The actuation of the actuator 234 is accomplished by adownwardly directed force which exerts a similar force to a patient'schest lying directly beneath the hydraulic cylinder 220.

[0086] The actuator 234 could be attached to a central piston whichcompresses a fluid within a hydraulic cylinder. Upon actuation ofactuator 234, the hydraulic fluid within the cylinder is compressed andis conveyed through the lines 222 and 224 and the pistons 226 and 228are driven inwardly as described above. This embodiment is alsoequivalent to the preferred embodiment.

[0087] It is possible to attach a power unit, such as a prime mover, tothe apparatus 10 which could function as an actuator to apply a lateralforce to the arm assemblies 16 and 18 to actuate them automatically andin regular, periodic intervals. As shown in FIG. 9, the power unit 254has a cable 256 which attaches to a belt 258. The device providing amechanical force to the belt 258 may be located in the power unit 254and the cable 256 is then rotatingly driven or longitudinally,reciprocatingly driven to tighten and loosen the belt 258.Alternatively, the actuator which tightens and loosens the belt 258could be located beneath the belt 258 and the cable 256 would merelyconvey electrical power or fluid pressure to the actuator. The powerunit 254 may use computer controls to time the application of force.

[0088] An example of a power unit 280 applying a force which tightens abelt 282 and depresses a base 284 is shown in FIG. 10. As the rod 286extends inwardly and outwardly of the power unit 280, the base 284 isdisplaced upwardly and downwardly, depressing the chest 288 as describedwith the preferred embodiment. Furthermore, this same mechanical motionof the rod 286 tightens and loosens the belt 282 as with the preferredembodiment.

[0089] In order to ensure that the patient's lungs are allowed to expandas much as desired, it may be necessary to include a full-releaseindicator with the present invention. This indicator should have somemeans for alerting the rescuer when full release of the tension on thebelt has not occurred. This indicator may include a limit switch, amagnet reed relay or contacts on the base 14 against which the armassemblies 16 and 18 rest in their relaxed position.

[0090] Instead of an indicator of full release, a mechanism could beadded to the arm assemblies 16 and 18 for preventing the application offorce to the handles 30 and 32 until full release (and return to therelaxed position) has occurred. A ratchet mechanism having discreetspacings could be used for this purpose. Additionally, such mechanismsare commonly found on electrical crimping tools for loose terminals.

[0091] It is possible to build into the force converter a mechanism forstoring and suddenly releasing energy during the application of adownward force. The sudden release would be actuated during thewithdrawal of the downward force, applying a short duration, highintensity force to the chest rather than a long duration application offorce as with the preferred embodiment.

[0092] It is preferred that the apparatus which rests on the top of apatient's chest be as light in weight as possible. The reason for thisis that after the patient's chest has been fully compressed, any weightwhich rests on top of the chest will tend to resist decompression of thechest once the compression force is removed. Reducing this weightminimizes the amount of unwanted compression during release anddecompression of the chest.

[0093] The adhesive pad 500 shown in FIG. 16 could contain an electrodewhich is electrically attached to a voltage generating device as isconventionally known. The adhesive pad 500 could be used in combinationwith one or more electrodes 504 interposed along the length of the belt506 or embedded in the backboard 508. These electrodes are used in theconventional manner to induce a current through the chest 510 which isused for defibrillating the patient's heart. Any combination of two ormore electrodes can be used to induce a current to defibrillate theheart.

[0094] The electrodes 504 can be interposed at multiple positions alongthe length of the belt 506 or in the backboard 508, but there willpreferably be a minimum of one electrode on the base 512 (such as theadhesive pad 500 which functions as an electrode) in addition to atleast one other electrode 504. The reason it is desirable to have anelectrode at least on the base 512 is that at the furthest extent ofcompression of the chest 510, the distance between the anterior andposterior outer surfaces of the chest 510 will be at a minimum, and thebase 512 will be positioned closer to the heart than at any other pointin the whole compression/decompression cycle. At this point there is aminimum of resistance to the flow of current which gives the greatestcurrent flow through the heart with the least likelihood of injuring thepatient's chest 510 tissue.

[0095] The electrodes 504 can be positioned not only circumferentiallyabout the chest 510, but can also be positioned at the samecircumferential location but at various longitudinal spacings.

[0096] It is preferred that a means be adapted to limit the travel ofthe assemblies 416 and 418 shown in FIG. 13 to only permit theassemblies 416 and 418 to move equal amounts relative to the base. It isundesirable for one assembly to move to one side more than the otherassembly, since this causes an imbalance in the application of force,which may result in injury to the patient. The injury arises when agreater force is applied to one edge of the base than the opposite. Thiscan occur if one of the two assemblies 416 and 418 moves a substantiallygreater distance than the other assembly. One means for limiting theirrelative motion is a pin in aligned slots in the arms. Another is a gearmechanism connected to both assemblies 416 and 418.

[0097] While certain preferred embodiments of the present invention havebeen disclosed in detail, it is to be understood that variousmodifications may be adopted without departing from the spirit of theinvention or scope of the following claims.

1. An apparatus for increasing the flow of blood in a patient, theapparatus comprising: (a) a base contoured to seat near a central regionof the patient's chest; (b) a manual actuator; (c) a substantiallyinelastic belt for wrapping around the chest; and (d) a force convertermounted on the base, connected to the actuator and having beltconnectors for connecting to opposite first and second extremities ofthe belt, for converting a force manually applied to the actuator anddirected toward the chest into a chest compressing resultant directedthrough the base toward the chest and belt tightening resultants appliedto the belt connectors directed tangential to the chest.
 2. An apparatusin accordance with claim 1, wherein the manual actuator comprises firstand second hand grippable handles.
 3. An apparatus in accordance withclaim 2, wherein the converter comprises: (a) a first arm having ahandle end to which the first handle is mounted and having an opposite,belt end to which a first extremity of the belt is attached, said firstarm being pivotally mounted to the base at a first arm fulcrumintermediate the handle end and the belt end; and (b) a second armhaving a handle end to which the second handle is mounted and having anopposite, belt end to which a second extremity of the belt is attached,said second arm pivotally mounted to the base at a second arm fulcrumintermediate the handle end and the belt end.
 4. An apparatus inaccordance with claim 2, wherein the converter comprises: (a) a firstassembly having a pair of spaced, parallel arms rigidly connected athandle ends by the first handle, the arms rigidly connected at opposite,belt ends by a first strut, and the arms pivotally mounted to the baseat a first assembly fulcrum intermediate the handle and belt ends; and(b) a second assembly having a pair of spaced, parallel arms rigidlyconnected at handle ends by the second handle, the arms rigidlyconnected at opposite, belt ends by a second strut, and the armspivotally mounted to the base at a second assembly fulcrum intermediatethe handle and belt ends.
 5. An apparatus in accordance with claim 4,wherein one of the arms of the first assembly pair and one of the armsof the second assembly pair are mounted to a side of the base, and theother arm of the first assembly pair and the other arm of the secondassembly pair are mounted to an opposite side of the base.
 6. Anapparatus in accordance with claim 5, wherein the assembly fulcrumscoincide at a pivot pin extending through all the arms of the assembliesand through the base.
 7. An apparatus in accordance with claim 6,wherein the belt ends and the handle ends of the arms have longitudinalaxes, and the belt end axis of each arm is transverse to the handle endaxis of the same arm.
 8. An apparatus in accordance with claim 7,wherein an angle of about 120° is formed between the belt end axis ofeach arm and the handle end axis of the same arm.
 9. An apparatus inaccordance with claim 4, wherein the first belt extremity is conformedto attach to the belt end of at least one arm of each assembly and thesecond belt extremity is conformed to attach to the belt end of at leastone arm of each assembly.
 10. An apparatus in accordance with claim 4,wherein the first belt extremity is conformed to attach to the firststrut, the second belt extremity is conformed to attach to the secondstrut.
 11. An apparatus in accordance with claim 10, further comprisingfasteners mounted to the extremities of the belt.
 12. An apparatus inaccordance with claim 11, wherein the fasteners comprise hooks and loopsmaterial.
 13. An apparatus in accordance with claim 11, furthercomprising indicia imprinted on a surface of the belt corresponding to alength of each belt extremity.
 14. An apparatus in accordance with claim13, wherein the indicia are colored bands oriented transverse to alongitudinal axis of the belt.
 15. An apparatus in accordance with claim5, wherein a pair of stroke limiting bars is pivotally mounted to thepair of arms of the first assembly, between the fulcrums and the handleends of each of the arms, extending to sliding attachment with the pairof arms of the second assembly, each of said stroke limiting barsextending between arms mounted to the same end of the base for limitingthe relative displacement of the attached arms.
 16. An apparatus inaccordance with claim 15, wherein the stroke limiting bars areadjustably, slidably attached to the pair of arms of the secondassembly, for adjusting stroke limitation.
 17. An apparatus inaccordance with claim 4, further comprising a rigid, substantiallyplanar backboard to which the belt is attached.
 18. An apparatus inaccordance with claim 17, wherein the backboard has two spaced, parallelslots through which the belt extends.
 19. An apparatus in accordancewith claim 18, wherein the backboard has a raised portion, integral witha planar portion, conformed to receive and support a patient's neckabove the planar portion.
 20. An apparatus in accordance with claim 19,further comprising a pressurized gas container, hose and breathing maskhoused within the backboard, beneath the raised portion.
 21. Anapparatus in accordance with claim 20, further comprising a force sensoron a chest contacting surface of the base, and a force indicator mountedto the base.
 22. An apparatus in accordance with claim 21, furthercomprising a signal generator, mounted to the base, for producingperiodic signals.
 23. A method of treating patients comprising: (a)seating a base of a blood flow increasing apparatus on a patient's chestnear a central region of the chest; (b) wrapping a belt around thepatient's chest; (c) fastening first and second opposite extremities ofthe belt to the apparatus; (d) applying a force, directed toward thechest, to a manual actuator mounted to a converter, said converterconnected to the base and the belt, configured to convert the force intoa chest compressing resultant directed toward the chest and belttightening resultants directed tangentially to the chest.
 24. A methodin accordance with claim 23, wherein applying the force furthercomprises grasping a pair of hand grippable handles and applying a forcehaving a component directed toward the chest.
 25. An apparatus forincreasing the flow of blood in a patient, the apparatus comprising: (a)a base configured to seat near a central region of a patient's chest;(b) an actuator; (c) a substantially inelastic belt configured to wraparound the chest; and (d) a force converter mounted on the base,connected to the actuator and having belt connectors for connecting toopposite extremities of the belt, for converting a force applied by theactuator into a chest compressing resultant directed toward the chestand belt tightening resultants directed tangentially to the chest. 26.An apparatus in accordance with claim 25, wherein the actuator comprisesa prime mover.
 27. An apparatus in accordance with claim 26, wherein theforce converter comprises: (a) a first arm having a handle end and anopposite, belt end to which a first extremity of the belt is attached,said first arm being pivotally mounted to the base at a first armfulcrum intermediate the handle end and the belt end; and (b) a secondarm having a handle end to which the second handle is mounted and havingan opposite, second belt extremity to which a second end of the belt isattached, said second arm pivotally mounted to the base at a second armfulcrum intermediate the handle end and the belt end.
 28. An apparatusin accordance with claim 26, wherein the converting means comprises: (a)a first assembly having a pair of spaced, parallel arms rigidlyconnected at handle ends by the first handle, the arms rigidly connectedat opposite, belt ends by a first strut, and the arms pivotally mountedto the base at a first assembly fulcrum intermediate the handle and beltends; and (b) a second assembly having a pair of spaced, parallel armsrigidly connected at handle ends by the second handle, the arms rigidlyconnected at opposite, belt ends by a second strut, and the armspivotally mounted to the base at a second assembly fulcrum intermediatethe handle and belt ends.
 29. An apparatus in accordance with claim 28,wherein one of the arms of the first assembly pair and one of the armsof the second assembly pair are mounted to a side of the base, and theother arm of the first assembly pair and the other arm of the secondassembly pair are mounted to an opposite side of the base.
 30. Anapparatus in accordance with claim 29, wherein the assembly fulcrumscoincide at a pivot pin extending through all the arms of the assembliesand through the base.
 31. An apparatus in accordance with claim 6,wherein the arms are curved.
 32. An apparatus in accordance with claim5, further comprising at least one pair of facing shoulders formed on apair of opposing arms, one shoulder formed on each arm, to form a gapbetween the facing shoulders into which a stop pin extends, for limitingthe relative displacement of the opposing arms.
 33. An apparatus inaccordance with claim 5, further comprising: (a) three shoulders formedon each of two opposing arms, forming three gaps of different lengthbetween three pairs of facing shoulders; (b) an upright mounted to thebase and having three holes formed through the upright, each holecorresponding to one gap; and (c) a stop pin extending from insertion inone of the holes into one of the gaps, for adjustably limiting therelative displacement of the opposing arms.
 34. An apparatus inaccordance with claim 4, further comprising a means mounted on achest-contacting surface of the base for adhering the chest-contactingsurface of the base to the chest.
 35. An apparatus in accordance withclaim 34, wherein the means for adhering comprises a suction cup.
 36. Anapparatus in accordance with claim 34, wherein the means for adheringcomprises an adhesive.
 37. An apparatus in accordance with claim 1,further comprising a pair of spaced electrodes mounted to the apparatusfor contacting two spaced outer chest surfaces.
 38. An apparatus inaccordance with claim 37, wherein a first electrode is mounted to a baseouter, chest-contacting surface, and a second electrode is mounted to anapparatus chest-contacting surface which is spaced from the firstelectrode.
 39. An apparatus in accordance with claim 38, wherein thesecond electrode is mounted to the belt.
 40. An apparatus in accordancewith claim 39 further comprising a plurality of electrodes interposedalong a belt longitudinal axis.